Downton Abbey: 5 things you didn't know.

Which American 80's tv star is on the British period drama "Downton Abbey" on PBS. Do they film on a set? How did the ratings fare against the Super Bowl? These are things every Downton Abbey fan should know. We've got the answers...

1. 'Downton' marks the comeback of an '80s movie starMost of the "Downton" cast is filled with British actors unfamiliar to U.S. audiences. But you might recognize the woman playing Cora, the American wife of Lord Grantham: It's Elizabeth McGovern, who became a film star back in the 1980s, co-starring in "She's Having a Baby" (alongside Kevin Bacon), "Ordinary People," and "Ragtime" (which earned her an Oscar nomination). After more than a decade spent in TV-movie hell, McGovern is now back on Hollywood's radar with her acclaimed performance as the sweet-faced but iron-willed caretaker of Downton.